1. Technical Field of the Invention
This invention relates to cellular telephone networks, and more particularly, to foreign network registration of roaming cellular telephones.
2. Description of Related Art
In existing cellular telecommunication systems, when a subscriber leaves a home network and enters a visited network that does not have automatic roamer signaling with the subscriber's home network, that subscriber cannot originate calls until the subscriber is manually registered. With or without an operator's manual intervention, the roaming subscriber must be connected as a manual visitor with a validation against a clearinghouse or validation of a credit card. In addition, within the visited network, every time the subscriber roams from one mobile switching center (MSC) to another visited MSC, the subscriber must go through the same procedure to re-register as a manual roamer.
In some networks, the manual registration procedure must be repeated every time the subscriber originates a call. Additionally, in order to minimize fraudulent calls, no call delivery is provided to manual subscribers because subscriber records are kept only for the duration of each call.